Jeep OBD Codes: Meaning & Fixes

P0420 Powertrain The bank 1 catalytic converter no longer stores enough oxygen to clean the exhaust properly. Low P0300 Powertrain The engine computer sees misfires that jump between cylinders or hit several cylinders at once. High P0302 Powertrain Cylinder 2 keeps misfiring. On inline engines it's a middle cylinder, so rule out coolant… Moderate P0303 Powertrain Cylinder 3 is misfiring. Check whether it misses at idle or under load before you blame… Moderate P0304 Powertrain Cylinder 4 is misfiring. Its end or rear position makes water, oil and intake leaks common… Moderate P0335 Powertrain The engine computer lost the crankshaft position signal. Expect stalling or a crank-no-start. High

B1B02 Jeep · Body The airbag computer sees a break in the driver airbag's firing circuit, so it may not deploy… High C121C Jeep · Chassis The ESC module asked the engine to cut power and the PCM refused, so stability and traction… Low C14A7 Jeep · Chassis The drivetrain module couldn't move the Cherokee's PTU shift actuator, so four-wheel drive… Low C2200 Jeep · Chassis The ABS module found a fault in its own electronics and shut off ABS, traction and stability… Moderate C2217 Jeep · Chassis The electric power steering module found a fault inside itself and may reduce or cut steering… High P0105 Powertrain The PCM lost a usable signal from the manifold pressure sensor: dropouts, noise or values it… Moderate P0128 Powertrain The engine takes too long to warm up, which almost always points to a thermostat stuck open. Low P0300 Powertrain The engine computer sees misfires that jump between cylinders or hit several cylinders at once. High P0302 Powertrain Cylinder 2 keeps misfiring. On inline engines it's a middle cylinder, so rule out coolant… Moderate P0303 Powertrain Cylinder 3 is misfiring. Check whether it misses at idle or under load before you blame… Moderate P0304 Powertrain Cylinder 4 is misfiring. Its end or rear position makes water, oil and intake leaks common… Moderate P0335 Powertrain The engine computer lost the crankshaft position signal. Expect stalling or a crank-no-start. High P0420 Powertrain The bank 1 catalytic converter no longer stores enough oxygen to clean the exhaust properly. Low P0456 Powertrain The EVAP system has a tiny leak, about 0.020 inch — the hardest EVAP leak to find, and often… Minor P0520 Powertrain The engine computer gets a signal from the oil pressure sensor or switch that makes no… Moderate P0521 Powertrain The oil pressure reading doesn't fit engine speed and temperature – a drifting sensor or truly… High P0622 Powertrain The alternator's field control or field feedback circuit is faulty – output may drop out… Moderate P0740 Powertrain The computer found an open or faulty circuit to the torque converter clutch solenoid, so lockup… Low P0887 Powertrain The circuit that switches the transmission power relay reads high voltage when it shouldn't. Moderate P1128 Jeep · Powertrain Your Jeep's PCM never switched bank 1 from preset fueling to O2-sensor feedback after… Low P1129 Jeep · Powertrain The PCM couldn't switch bank 2 of your Jeep's V6 or V8 into oxygen-sensor-controlled fueling… Low P1281 Jeep · Powertrain Your Jeep's engine didn't reach operating temperature in time, most often due to a stuck-open… Low P1391 Jeep · Powertrain The PCM keeps briefly losing the cam or crank position signal, which can make your Jeep stumble… Moderate P1494 Jeep · Powertrain Your Jeep's EVAP leak detection pump was commanded to stroke, but its internal switch never… Minor P1495 Jeep · Powertrain The PCM found an open or short in the circuit that fires your Jeep's EVAP leak detection pump… Minor P1684 Jeep · Powertrain An informational code: your Jeep's PCM lost battery power at some point in the last 50 engine… Minor P1698 Jeep · Powertrain The engine computer stopped hearing from the transmission computer, often leaving the Jeep… Moderate P2101 Powertrain The throttle plate isn't reaching the position the computer asks for, fast enough or accurately… Moderate P2138 Powertrain The two sensors in the gas pedal report different pedal positions, so the PCM limits throttle… Moderate P2400 Powertrain The engine computer can't drive the EVAP leak detection pump – usually a broken wire, bad plug… Low